Effects of water stress on photosynthesis and carbon partitioning in soybean (Glycine max (L. ) Merr. ) plants grown in the field at different CO/sub 2/ levels

Journal Article · Sat Sep 01 04:00:00 EDT 1984 · Plant Physiol.; (United States)

OSTI ID:5974735

Huber, S C; Rogers, H H; Mowry, F L

The effects of water stress and CO/sub 2/ enrichment on photosynthesis, assimilate export, and sucrose-P synthase activity were examined in the field grown soybean plants. In general, leaves of plants grown in CO/sub 2/-enriched atmospheres (300 microliters per liter above unenriched control, which was 349 +/- 12 microliters per liter between 0500 and 1900 hours EST over the entire season) had higher carbon exchange rates (CER) compared to plants grown at ambient CO/sub 2/, but similar rates of export and similar activities of sucrose-P synthase. On most sample dates, essentially all of the extra carbon fixed as a result of CO/sub 2/ enrichment was partitioned into starch. CO/sub 2/-enriched plants had lower transpiration rates and therefore had a higher water use efficiency (milligrams CO/sub 2/ fixed per gram H/sub 2/O transpired) per unit leaf area compared to nonenriched plants. Water stress reduced CER in nonenriched plants to a greater extent than in CO/sub 2/-enriched plants. As CER declined, stomatal resistance increased, but this was not the primary cause of the decrease in assimilation because internal CO/sub 2/ concentration remained relatively constant. Export of assimilates was less affected by water stress than was CER. When CERs were low as a result of the imposed stress, export was supported by mobilization of reserves (mainly starch). Export rate and leaf sucrose concentration were related in a curvilinear manner. When sucrose concentration was above about 12 milligrams per square decimeter, obtained with nonstressed plants at high CO/sub 2/, there was no significant increase in export rate. Assimilate export rate was also correlated positively with SPS activity and the quantitative relationship varied with CER. Thus, export rate was a function of both CER and carbon partitioning. 28 references, 11 figures.

• Research Organization: North Carolina State Univ., Raleigh
• OSTI ID: 5974735
• Journal Information: Plant Physiol.; (United States), Journal Name: Plant Physiol.; (United States) Vol. 76:1; ISSN PLPHA
• Country of Publication: United States
• Language: English

Related Subjects

550500* -- Metabolism
59 BASIC BIOLOGICAL SCIENCES
AIR-WATER INTERACTIONS
BIOLOGICAL EFFECTS
BIOLOGICAL STRESS
CARBOHYDRATES
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
DISACCHARIDES
ELECTRON TRANSFER
ENZYME ACTIVITY
ENZYMES
ESTERASES
GLYCINE HISPIDA
HYDROGEN COMPOUNDS
HYDROLASES
LEAVES
LEGUMINOSAE
METABOLISM
OLIGOSACCHARIDES
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHOSPHATASES
PHOTOCHEMICAL REACTIONS
PHOTOSYNTHESIS
PLANTS
SACCHARIDES
SACCHAROSE
SYNTHESIS
WATER